CPEB

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CPEB, or cytoplasmic polyadenylation element binding protein, is a highly conserved RNA-binding protein that promotes the elongation of the polyadenine tail of messenger RNA.[1] CPEB most commonly activates the target RNA for translation, but can also act as a repressor,[2] dependent on its phosphorylation state.[3] In animals, CPEB is expressed in several alternative splicing isoforms that are specific to particular tissues and functions; CPEB was first identified in Xenopus oocytes and associated with meiosis;[1] a role has also been identified in the spermatogenesis of Caenorhabditis elegans.[4]

An isoform of CPEB found in the neurons of the sea slug Aplysia californica, as well as in Drosophila, mice, and humans, contains an N-terminal domain not found in other isoforms that shows high sequence similarity to prion proteins. Experiments with the Aplysia isoform expressed in yeast reveal that CPEB has a key property associated with prions: it can cause other proteins to assume alternate protein conformations that are heritable in successive generations of yeast cells. Furthermore, the functional RNA-binding form of the CPEB protein may be the prion-like state.[5] These observations have led to the suggesting that long-lasting bistable prionlike proteins play a role in the formation of long-term memory.[6]

References

  1. 1.0 1.1 Hake, L.E., and Richter, J.D. (1994). CPEB is a specificity factor that mediates cytoplasmic polyadenylation during Xenopus oocyte maturation. Cell 79, 617–627.
  2. de Moor, C.H., and Richter, J.D. (1999). Cytoplasmic polyadenylation mediate masking and unmasking of cyclin B1 mRNA. EMBO J. 18, 2294–2303.
  3. Mendez, R., Barnard, D., and Richter, J.D. (2002). Differential mRNA translation and meiotic progression require Cdc2-mediated CPEB destruction. EMBO J. 21, 1833–1844.
  4. Luitjens C, Gallegos M, Kraemer B, Kimble J, Wickens M. (2000). CPEB proteins control two key steps in spermatogenesis in C. elegans. Genes Dev 14(20):2596-609.
  5. Si K, Lindquist S, Kandel ER. (2003). A Neuronal Isoform of the Aplysia CPEB Has Prion-Like Properties. Cell 115: 879-91.
  6. Shorter J, Lindquist S (2005). "Prions as adaptive conduits of memory and inheritance". Nat Rev Genet 6 (6): 435-50. PMID 15931169

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